universal design perceptible information tolerance for error - - PDF document

1 chapter 10

universal design

universal design principles

• NCSW
• equitable use
• flexibility in use
• simple and intuitive to use
• perceptible information
• tolerance for error
• low physical effort
• size and space for approach and use

Multi-Sensory Systems

• More than one sensory channel in interaction

– e.g. sounds, text, hypertext, animation, video, gestures, vision

• Used in a range of applications:

– particularly good for users with special needs, and virtual reality

• Will cover

– general terminology – speech – non-speech sounds – handwriting

• considering applications as well as principles

Usable Senses

The 5 senses (sight, sound, touch, taste and sm ell) are used by us every day

– each is important on its own – together, they provide a fuller interaction with the natural world

Com puters rarely offer such a rich interaction Can we use all the available senses? – ideally, yes – practically – no We can use

• sight • sound • touch (som etim es)

We cannot (yet) use • taste • sm ell

Multi-modal vs. Multi-media

• Multi-modal systems

– use m ore than one sense (or m ode ) of interaction

e.g. visual and aural senses: a text processor may speak the words as well as echoing them to the screen

• Multi-m edia system s

– use a num ber of different m edia to com m unicate inform ation

e.g. a computer-based teaching system: may use video, animation, text and still images: different media all using the visual mode of interaction; may also use sounds, both speech and non-speech: two more media, now using a different mode

Speech

Human beings have a great and natural mastery of speech

– m akes it difficult to appreciate the complexities but – it’s an easy m edium for com m unication

2

Structure of Speech

phonemes

– 40 of them – basic atom ic units – sound slightly different depending on the context they are in, these larger units are …

allophones

– all the sounds in the language – between 120 and 130 of them – these are form ed into …

morphemes

– sm allest unit of language that has m eaning.

Speech (cont’d)

Other term inology:

• prosody

– alteration in tone and quality – variations in em phasis, stress, pauses and pitch – im part m ore m eaning to sentences.

• co-articulation

– the effect of context on the sound – transform s the phonem es into allophones

• syntax – structure of sentences
• sem antics – m eaning of sentences

Speech Recognition Problems

• Different people speak differently:

– accent, intonation, stress, idiom, volume, etc.

• The syntax of sem antically sim ilar sentences m ay vary.
• Background noises can interfere.
• People often “ um m m .....” and “errr.....”
• Words not enough - sem antics needed as well

– requires intelligence to understand a sentence – context of the utterance often has to be known – also information about the subject and speaker e.g. even if “ Errr.... I, um, don’t like this” is recognised, it is a fairly useless piece of information on it’s own

The Phonetic Typewriter

• Developed for Finnish (a phonetic language, written as it is said)
• Trained on one speaker, will generalise to others.
• A neural network is trained to cluster together sim ilar

sounds, which are then labelled with the corresponding character.

• When recognising speech, the sounds uttered are

allocated to the closest corresponding output, and the character for that output is printed.

– requires large dictionary of minor variations to correct general mechanism – noticeably poorer performance on speakers it has not been trained

• n

The Phonetic Typewriter (ctd)

a a a a a a

• l

l u m v h r ah æ p d s i y j g ø tk vm hj hi u u v v v v . . . . m a r r r h h h æ æ r m p p p p p d k k pt t t t ø ø e n e e l g n j j j j j i i i s s y y h r k h r h n n

Speech Recognition: useful?

• Single user or limited vocabulary systems

e.g. com puter dictation

• Open use, lim ited vocabulary system s can

work satisfactorily

e.g. som e voice activated telephone system s

• general user, wide vocabulary systems …

… still a problem

• Great potential, however

– when users hands are already occupied e.g. driving, manufacturing – for users with physical disabilities – lightweight, m obile devices

3

Speech Synthesis

The generation of speech Useful – natural and familiar way of receiving information Problem s – similar to recognition: prosody particularly Additional problem s – intrusive - needs headphones, or creates noise in the workplace – transient - harder to review and browse

Speech Synthesis: useful?

Successful in certain constrained applications when the user: – is particularly motivated to overcome problems – has few alternatives Exam ples:

• screen readers

– read the textual display to the user utilised by visually impaired people

• warning signals

– spoken information sometimes presented to pilots whose visual and haptic skills are already fully occupied

Non-Speech Sounds

boings, bangs, squeaks, clicks etc.

• commonly used for warnings and alarms
• Evidence to show they are useful

– fewer typing m istakes with key clicks – video gam es harder without sound

• Language/ culture independent, unlike speech

Non-Speech Sounds: useful?

• Dual m ode displays:

– information presented along two different sensory channels – redundant presentation of information – resolution of ambiguity in one mode through information in another

• Sound good for

– transient information – background status information e.g. Sound can be used as a redundant mode in the Apple Macintosh; almost any user action (file selection, window active, disk insert, search error, copy complete, etc.) can have a different sound associated with it.

Auditory Icons

• Use natural sounds to represent different types of
• bject or action
• Natural sounds have associated sem antics which can be

m apped onto sim ilar m eanings in the interaction

e.g. throwing something away ~ the sound of smashing glass

• Problem : not all things have associated m eanings
• Additional inform ation can also be presented:

– muffled sounds if object is obscured or action is in the background – use of stereo allows positional information to be added

SonicFinder for the Macintosh

• item s and actions on the desktop have

associated sounds

• folders have a papery noise
• m oving files – dragging sound
• copying – a problem …

sound of a liquid being poured into a receptacle rising pitch indicates the progress of the copy

• big files have louder sound than sm aller ones

4

Earcons

• Synthetic sounds used to convey information
• Structured combinations of notes (motives )

represent actions and objects

• Motives com bined to provide rich inform ation

– com pound earcons – m ultiple m otives com bined to m ake one m ore com plicated earcon

Earcons (ctd)

• family earcons

sim ilar types of earcons represent sim ilar classes of action or sim ilar objects: the fam ily of “ errors” would contain syntax and operating system errors

• Earcons easily grouped and refined due to

com positional and hierarchical nature

• Harder to associate with the interface task

since there is no natural mapping

touch

• haptic interaction

– cutaneous perception

• tactile sensation; vibrations on the skin

– kinesthetics

• movement and position; force feedback
• information on shape, texture, resistance,

temperature, comparative spatial factors

• example technologies

– electronic braille displays – force feedback devices e.g. Phantom

• resistance, texture

Handwriting recognition

Handwriting is another com m unication m echanism which we are used to in day-to-day life

• Technology

– Handwriting consists of com plex strokes and spaces – Captured by digitising tablet

• strokes transformed to sequence of dots

– large tablets available

• suitable for digitising maps and technical drawings

– sm aller devices, som e incorporating thin screens to display the inform ation

• PDAs such as Palm Pilot
• tablet PCs

Handwriting recognition (ctd)

• Problem s

– personal differences in letter form ation – co-articulation effects

• Breakthroughs:

– stroke not just bitm ap – special ‘alphabet’ – Graffeti on PalmOS

• Current state:

– usable – even without training – but m any prefer keyboards!

gesture

• applications

– gestural input - e.g. “ put that there” – sign language

• technology

– data glove – position sensing devices e.g MI T Media Room

• benefits

– natural form of interaction - pointing – enhance com m unication between signing and non- signing users

• problem s

– user dependent, variable and issues of coarticulation

5

Users with disabilities

• visual im pairm ent

– screen readers, SonicFinder

• hearing im pairm ent

– text communication, gesture, captions

• physical im pairm ent

– speech I/ O, eyegaze, gesture, predictive systems (e.g. Reactive keyboard)

• speech im pairm ent

– speech synthesis, text communication

• dyslexia

– speech input, output

• autism

– communication, education

… plus …

• age groups

– older people e.g. disability aids, m em ory aids, com m unication tools to prevent social isolation – children e.g. appropriate input/ output devices, involvem ent in design process

• cultural differences

– influence of nationality, generation, gender, race, sexuality, class, religion, political persuasion etc. on interpretation of interface features – e.g. interpretation and acceptability of language, cultural sym bols, gesture and colour